The present invention relates to apparatus for effectively achieving optimum/preferred compaction and moisture content of earthen materials such as soil, as required prior to constructing, applying lifts of fill material or paving thereover.
Prior to erecting structures, lifting fill areas or paving parking lots for commercial use, the soil thereunder has to be analyzed by a geotechnical engineer using a troxler probe which analyzes the present condition of the soil which then must match laboratory information such as specific density and moisture content. If these conditions are not to the satisfaction of the geotechnical engineer, the material may have to be fluffed with machinery to dry in the sun and then recompacted after the proper moisture content is attained, or worse yet, the material may have to be removed and exported and suitable new material imported and substituted in its place. This of course causes an expensive loss of time and production, particularly during extensive rain periods, with the possible penalty inducing on tight deadlines. It can further cause the application of penalty fines and the shutting down of jobs because of silt and erosion problems.
The apparatus of the present invention for drying and compacting earthen materials such as soil, includes in combination a vehicle, such as a motorized tractor, and a microwave applicator attached to the vehicle. The microwave applicator includes a microwave permeable drum for rolling over the ground surface, and a microwave heater element including a magnetron fuse and wave guide assembly (magnetron fuse rod) is disposed in the drum for emitting and directing microwaves downwardly through the drum into underlying soil to be dried. The microwave applicator further includes an electrical generator, a high voltage transformer, and a control that are mounted on the vehicle for regulating the intensity of microwave energy emitted from the magnetron fuse in relation to the present condition of the material on hand to be treated.
The vehicle includes an operator""s cab which has microwave nonpermeable shielding for protecting the operator in the cab from microwave contamination when operating the equipment. A microwave nonpermeable shield cover is also provided over the side and upper surfaces of the drum to prevent microwave radiation from escaping to unwanted areas. A microwave reflective inner lining is also provided in the cover for reflecting microwaves downwardly into the underlying soil. Furthermore, a triple layer ground hugging skirt is provided to seal the base of the shield to the ground. Internal steam and heat exhaust is forced by fans through a microwave baffle port making the entire microwave applicator assembly a microwave tight system.
A compactor is also preferably attached to the vehicle for compacting the underlying soil. Generally the compactor will be a vibratory roller compactor that is attached to the rear end of the motorized tractor vehicle, and the drum with the microwave heating element is attached to the front end of the vehicle.
Cooling is also provided for the drum and the microwave heater element contained therein and will generally be provided in the form of one or more motorized fans mounted inside the drum with ventilation apertures provided in the ends of the drum. Additional cooling may be provided by including one or more fans mounted on the shield cover which covers over the side and upper surfaces of the drum for thereby moving cooling air over the drum.
The microwave heater element will normally include a magnetron fuse rod coaxially mounted in the drum and an electric generator is mounted on the motorized tractor vehicle which transmits electricity to a high voltage transformer and then in turn to the magnetron fuse rod for energization thereof to provide microwave emission.
The motorized vehicle will normally be provided in the form of a motorized tractor with dual tracks that have elastomer tread guard inserts in order to protect surfaces over which it rides. A track vehicle is suggested as opposed to a articulating dual roller device to provide traction and less down pressure in even the worst of conditions.